Renal cell carcinoma (RCC) accounts for about 3% of all malignant tumors in adults. Its worldwide incidence and mortality are approximately 209,000 and 102,000 per year respectively, including 39,000 new cases and 13,000 deaths in the United States (Gupta et al. 2008). Clear cell RCC (ccRCC) represents the most common renal cancer histology, comprising 70-80% of all RCC cases (Rini et al. 2009). About 30% of patients with newly diagnosed disease have evidence of metastases at presentation (Landis et al 1999). Once RCC has metastasized, few patients achieve a durable remission. Only about 15-25% of patients having metastatic RCC respond to currently available therapies and the overall median survival is less than one year (Gupta et al. 2008). RCC metastasis cannot be predicted reliably based on patients' clinical manifestations, pathologic findings or other currently available laboratory tests.
Although several algorithms have been used to predict clinical outcome for patients with metastatic RCC (mRCC) on the basis of clinical and pathologic features, these do not incorporate the more complex biological features of individual patients (Rini et al. 2009; Zisman et al. 2001). Recent studies have shown that the metastatic capability of cancer is conferred by genetic changes that occur relatively early in tumorigenesis and that metastatic dissemination may occur continually throughout the course of primary tumor development (Weinberg 2008; Klein 2008; Coghlin 2010).
Early detection of ccRCC metastatic potential may be beneficial for a more precise prediction of clinical outcomes and may ultimately be used to identify subsets of patients that may benefit from specific targeted therapies. Therefore, it is desired to identify metastasis-specific molecular biomarkers at the time of nephrectomy to predict ccRCC metastasis.